This manga follows the adventures of a group of mercenaries: the barbarian Mocha (the main character), the rogue Buruman, and the mage Kiliman (Blue Mountain and Killie Mountain, respectively, are famous coffee brands in Japan).
Mocha and her gang belong to a dark mercenary guild. Mocha, being a barbarian, has great physical strength and, of course, she has no brain. Despite her very revealing suit, she is very innocent, pure and naive. The story starts when a light master seeks to hire some mercenaries, and the guild refuses to help him since he has no money with him. So the dark guild master sends Mocha, Buruman, and Kiliman to aid him. It's really not a great start but this is how everything begins.